Method and apparatus in moistening of a web

ABSTRACT

In the method in moistening of a web, water is applied with a wetting device ( 2 ) in a predetermined point on the surface of a paper web (W) or the like passing by the point, and the web is thereafter passed to a calender (C). The liquid is applied at such an early stage that before the surface treatment, the fibres exposed to wetting in the paper web (W) or the like have the time to absorb it at least 80% of the amount of liquid they are capable of absorbing. The distance travelled by the web between the drying section and the calender is increased with rolls ( 1 ) which guide the web (W) along a winding path.

FIELD OF THE INVENTION

The invention relates to a method in moistening of a web, in whichliquid is applied in a predetermined point on the surface of a paper webor the like moving past the point, whereafter the web is guided tosurface treatment. In particular, the invention relates to a method inwhich the surface of a paper web is wetted in a wetting unit in thepaper machine before the web is calendered. The invention also relatesto an apparatus for implementing the aforementioned method. Hereinbelow,the term paper web refers to all materials in the form of a flexible webmade of fibrous material and capable of absorbing liquid.

BACKGROUND OF THE INVENTION

After the paper has been dried, the surface structure of a web is madesuitable by means of a mechanical treatment, calendering. There areseveral calendering methods, but it is common to all of them that theweb is passed through one or several nips which are formed between twosurfaces, typically between rotating roll surfaces. The purpose of thecalendering is to improve the paper quality by pressing the paper into afixed final thickness, and especially by smoothing its surface. As iswell known, the mouldability of the fibres contained in the paper orpaperboard, the “plasticization” of the web in connection with thecalendering, can be improved by increasing the temperature and/ormoisture. The mouldability of the polymers contained in the paper can beincreased by raising the treatment temperature to or above their glasstransition temperature. By increasing the moisture content it is, inturn, possible to lower the glass transition temperature. It is oftenadvantageous to restrict the impact of the temperature and moisture onlyon either surface layer or on both surface layers of the web, whereinthe mouldability of their fibres can be improved without excessivelyaffecting the central layer of the web. As a result of this, a knownprocedure is the wetting of the surfaces of the web before thecalendering of the web. Another known procedure is the adding of steambefore the nip between the calender rolls, wherein a preheating of thesurface is also attained. Calendering processes are presented forexample in the European patent 617165.

At present, the manufacture of SC paper requires so-called overdrying ofthe paper. This means that the paper is dried before calendering into amoisture which is smaller than its moisture of use. Maximally this meansthat the paper is dried very dry down into a moisture range of 1.5 to2.5.

Overdrying is well founded, because the moisture expansion potential ofthe paper is reduced when the smallest moisture content which itexperiences during the papermaking is reduced. Small moisture expansionpotential improves the printability of the product. Furthermore, atpresent, overdrying and re-wetting produce better profiles in view ofcalendering when compared to drying of the paper directly to the targetinlet moisture of the calendering.

Particularly in the manufacturing processes of SC paper the paper has tobe wetted to attain the correct target moisture. In Off-line processesthe wetting and the location in which it is conducted are not verycrucial, because the moisture profiles, tensions and other correspondingvariables of the paper have the time to be sufficiently equalized in thereel field before supercalendering. In on-line processes, in turn, it isimportant to reach the correct moisture of the paper before calendering.

The problem in the wetting of a web in the form of a continuous strip isthat it is difficult to set the water content absolutely accurately toattain the desired moisture gradient in the thickness direction of theweb. There is a risk that the moisture gradient is set too low, and theflattening effect of the calendering is unnecessarily directed to thecentral layer of the web instead of being directed in a most appropriatemanner to the surface fibres of the web. However, in view of the finalquality of the paper or paperboard, it is important that the calenderingis successful. Thus, a correct dosage of water is the basic conditionfor a successful surface treatment.

To attain a sufficiently steep moisture gradient, it is possible to usearrangements known as such which relate to the structure and/orplacement of wetting devices, but despite these arrangements themoisture gradient can be disadvantageous when the web enters thecalender. Thus, the problems relate to the build-up of a correctmoisture gradient as a result of the absorption of water taking placeafter the wetting devices. It is possible that after the wetting theabsorption of water in the web before the calender is insufficient, ortoo much water is absorbed in the web. Similarly, it is a problem thatwith water the desired effect is not attained in the calendering. Thismay result in that the web remains unevenly wetted, the central layer ofthe web is unnecessarily wetted, or the fibres will be insufficientlymoulded in the nip.

A known manner is to arrange the wetting devices in connection with thecalender very close to the calender nip, as is presented e.g. in theEuropean patent 617165 and in the U.S. Pat. No. 4,945,654.

OBJECTS AND SUMMARY OF THE INVENTION

It is a purpose of the invention to reduce the aforementioned problemsand to introduce a method by means of which the intended wetting can beachieved. To attain this purpose, the method according to the inventionis primarily characterized in that liquid is applied at such an earlystage that the fibres exposed to wetting in the paper web or the likehave time to absorb the liquid at least 80% of the total amount ofliquid they are capable of absorbing before the surface is treated. Theweb is guided to surface treatment in the moisture content obtained byadding the liquid.

The period of time during which the wetting is effective after thewetting can be influenced especially by adjusting the distance travelledby the web from the wetting point, which can be implemented e.g. bychanging the respective location of the rolls in the roll system guidingthe web in such a way that the overall length of the path of the web inthe roll system is changed.

The invention is based on the observation that in the end, only anoptimal influence time of the wetting on the web when it travels fromthe wetting devices to the calender, is capable of ensuring the intendedmoisture effect. The web is wetted into the target moisture, and it isguided in this moisture into the calender nip.

Other features characteristic to the method according to the inventionappear in the appended dependent claims, which present additionaladjustment manners and possibilities to influence the uniformity of thewetting.

The apparatus according to the invention comprises a device for addingliquid, which is placed at such a distance from the device conductingsurface treatment, taking into account the speed of the web, that theliquid added to the web will have time to be absorbed in the fibresexposed to wetting in the web at least 80% of the total amount of liquidwhich the fibres are capable of absorbing.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in more detail withreference to the appended drawings, in which

FIG. 1 shows the principle of the method according to the invention, andat the same time the apparatus according to the invention in a sideview,

FIGS. 2 to 5 illustrate the absorption of water and the effect of thewater amount,

FIG. 6 illustrates the dosage of water and its adjustment principle toattain an even two-dimensional application, and

FIG. 7a is an elevational view depicting turbulence zones associatedwith prior art spraying techniques,

FIG. 7b shows an advantageous manner to attain an even applicationtwo-dimensionally with respect to the plane of the web.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows schematically a paper or paperboard web W coming from adrying section in a paper or paperboard machine, which web W is passedvia a wetting unit to a calender C. The wetting unit comprises at leastone wetting device 2, by means of which one surface of the web W ismoistened in a way known as such, and which wetting device 2 canfunction in any one of the following principles:

spray wetting,

film transfer wetting (LAS, sym-sizer etc.),

moistening by adjusting the relative humidity of air,

steaming, if necessary combined with the cooling of the web beforesteaming,

Naturally, in two-sided wetting, it is possible to use different wettingprinciples on different sides of the web W. In the wetting the web Wobtains the desired surface moisture, and it is passed in this moisturein the calender nip N of the calender. The calender may be of a knowncalender type, but the invention is applicable especially before anon-line calender which contains over four nips, such as a calenderformed of successive roll pairs or a stack of calender rolls shown inthe drawing. The invention is applicable especially in the manufacturingprocess of SC paper before on-line calendering effected withaforementioned multi-nip calender types.

As can be seen in FIG. 1, there is a wetting device 2 on both sides ofthe web W. On both sides there are also several successive wettingdevices 2, in FIG. 1 two wetting devices.

Because, however, there occurs absorption of moisture in the surfacelayers of the web W in the wetted web W after the wetting, and from thesurface layers further into the central layer of the web W, it isnecessary to set the overall length of the path of the web between thelast wetting device 2 and the nip N of the calender in such a way thatthe arrival of the web in the calender C lasts for a period of timeafter which the web W has been wetted optimally in view of calendering.In other words, the web is sufficiently wetted especially in its outerlayers while the central layer remains substantially drier in such a waythat a sufficiently steep moisture gradient is produced in the web W inits z-direction (i.e., perpendicular to a surface of the web).

The period of time is especially such that the fibres exposed to wettinghave the time to absorb at least 80% of the water amount they arecapable of absorbing, of the water added in the wetting on the same sideof the web W from one or more wetting devices 1. The term absorptionrefers to the swelling of paper web fibres, typically wood fibres, whichconsists of water adsorption, absorption, diffusion transfer of water tothe fibre, as well as of a transfer induced by osmotic pressure, inother words the swelling of the fibres should be at least 80%.

In practice, the sufficient absorption of water into the fibres takesapproximately 0.3 s, at the shortest. FIG. 2 shows the water sorptiontimes of single fibres measured in laboratory conditions. For singlefibres the relevant water amount in view of calendering would beapproximately 80% of the maximum, i.e. the corresponding absorption timewould thus be approximately 200 ms. In practice, the fibres are notdisposed individually, but they are tightly connected together in thenetwork structure of the paper, and the network structure of the paperas well as the application conditions of the water decelerate theabsorption of water in such a way that the presumable minimum time isthe aforementioned 0.3 s. In some advantageous conditions, the minimumtime can be 0.2 s, including a small safety margin.

The optimal application time naturally depends on the fibrous materialand the surface chemistry of the paper, as well as on the networkstructure. As a result of the transition from chemical pulps towardsmechanical pulp the necessary absorption time is increased. Therefore itis advantageous to apply the water 0.2 to 2 s, advantageously 0.3 to 2 sbefore the nip, depending on the paper grade. The most advantageousabsorption time of most processes is 0.5 to 1.0 s. For example in themanufacturing process of paperboard, the running speeds can be 600m/min. Thus, it is advantageous to place the wetting device in adistance of 2 to 10 m from the first calender nip (corresponding thetime of 0.2 to 1.0 s). In a typical manufacturing process of SC paperthe running speed can be 1500 m/min. Thus, it is advantageous to placethe wetting device 5 to 25 m before the first calender nip(corresponding the time of 0.2 to 1.0 s).

On the other hand, water breaks the bonds between the fibres in thepaper, relaxes the tensions developed during the drying in the paper,and generates hydroexpansion of paper, which reduces the effect ofstreaks (variable moisture cross profile) resulting from the dryingsection and equalizes the cross profile of the paper. For example in SCpapers, to implement the aforementioned processes the optimum result ofthe wetting is to be expected within the period of 500 to 1500 ms,advantageously 600 to 1300 ms, which at the running speed of 1500 m/mincorresponds to the distance of 12.5 to 37.5 m and 15 to 32.5 m,respectively.

In machines utilizing high running speeds it is thus basicallyadvantageous to place the wetting device as far as possible before thecalender. The upper limit of the placement distance of the wettingdevice is determined on the basis of the structure of the paper machineand/or the moisture retention. If the wetting device is placed too farbefore the first calender nip, it is possible that re-drying takes placein the web. This takes place especially if the wetting device is insidethe drying section e.g. before the last dryer group. An advantageouslocation point in all paper or paperboard machines and especially in SCpaper machines, is at the most 40 m, advantageously at the most 35 mbefore the first calender nip of the calender, and advantageously afterthe drying section. In high-speed machines the long placement distancerequired by the speed and measured along the travel path of the web canbe implemented, irrespective of the straight fixed distance of thedrying section and the calender in the machine direction, with anarrangement which will be described hereinbelow.

Sufficient absorption time ensures that the polymers contained in thefibrous material of the paper are plasticized by the effect of water.This, in turn, improves the calendering result considerably. FIGS. 3 and4 show the development of PPS as a function of the absorption time withdifferent added quantities, wherein FIG. 3 shows the results on theupper side of unsprayed SC paper and FIG. 4 the results on the lowerside of sprayed SC paper. In the drawings, the water amount “−1” denotesan increase of 1 g/m², “0” an increase of 1.8 g/m² and “1” an increaseof 2.8 g/m². FIG. 5 shows the development of density as a function ofthe absorption time, and it also describes the experiment conditions ofFIGS. 3 and 4.

In conventional solutions there is not enough time for the water to besufficiently absorbed. Thus, the effect of the water is primarily basedon its bond-breaking effect between the fibres, wherein the surfacelayer of the paper is slackened and its mouldability is improved as aresult of this. The method according to the invention utilizes bothpositive effects of the water, thus enhancing the calenderingconsiderably. Thus, the applied water amount is larger than the amountwhich would be necessary for wetting the fibres with the actualadsorption, i.e. there is also free water between the fibres in thesurface layer of the web.

Long influence time is advantageous also in view of the result ofapplying the liquid. If the liquid is applied on the surface of the webW by spraying in droplets, the film in question is discontinuous even inbest spraying processes. To avoid drop marks, the liquid is given timeto spread in the direction of the plane of the web. Thus, it is possibleto avoid small-scale gloss variations of the paper resulting from theuneven liquid film.

In the following, an advantageous manner of passing the web on theportion between the drying section and the calender will be described.

Since the distance travelled by the web from the wetting point to thecalender is relatively long in high-speed machines to ensure asufficient absorption time, it is advantageous to arrange the web W totravel along a winding or meandering path by guiding it between upperrolls 1 and lower rolls 1 in a roll system T arranged between the dryingsection and the calender. Thus, the distance can be increasedirrespective of the horizontal distances available in the paper machine.The rolls 1 are located after the wetting device 2. As shown in FIG. 1,between two successive wetting devices 2 which wet the same side of theweb there is a roll 1 by means of which the distance of the wettingdevices from each other can be increased.

The distance between the wetting device 2 and the nip N can also beaffected by changing the mutual location of the rolls 1 in the rollsystem T in such a way that the overall length of the path of the web Win the portion of the roll system T is changed. To implement this, thelocation of at least one roll 1 in the roll system T is changed, i.e.the distance between two successive rolls 1 is changed, wherein theoverall length of the path between the first and the last roll 1 of theroll system T is changed. To change the distance, the roll 1 can bemoved in the longitudinal direction of the wetting unit and/or in itsheight direction, but it is obvious that in view of the space economyrequired by the paper machine, the transfer of the roll 1 substantiallyin the height direction is the most advantageous embodiment.

Similarly, by moving the roll 1 between the wetting devices 2, it ispossible to change the distance between the wetting devices 2 withoutmoving them.

With regard to implementing the purpose of the invention, it isadvantageous that- instead of the possibility of moving one roll 1,several rolls 1 are arranged movable in the roll system T simultaneouslyor at different times. Thus, it is typical for the wetting unit that therolls 1 are arranged to form special roll rows TR (preferably two on topof each other, as shown in the drawing), which is advantageous in viewof the space economy of the paper or paperboard machine. Thus, anadvantageous embodiment of the invention is such where an entire rollrow TR is arranged to be moved especially substantially in the heightdirection in relation to the second roll line TR or other roll row TR.

To move the rolls 1 and/or roll rows TR it is possible to use forcedevice arrangements, power transmission arrangements, control automationarrangements or corresponding arrangements known as such in connectionwith the papermachine technology. Especially for the transfer of anentire roll row TR, necessary support structure, coupling and othercorresponding arrangements for simultaneous motion of the rolls areprovided, which arrangements are based on prior art. It is obvious thatby means of said arrangements it is possible to implement an embodimentin which either one or more rolls 1 can be moved separately in additionto moving the entire roll row TR.

The aforementioned facts also apply in the special case where thewetting unit is provided with only one roll 1, wherein the shortestoverall length of the path of the web W is substantially formed of thestraight line between the wetting device 2 and the calender C, and thetotal length can be increased by turning the path of the web W with theroll 1. When the aforementioned distances of several metres are takeninto account, a more advantageous solution entails at least two rolls 1or the like which increase the travel path of the web. A multiple-rollstructure with at least three rolls 1 or the like between the wettingdevice 2 and the calender C, is the most advantageous one.

It is possible to think that the rolls 1 are replaced with any othermeans which guide the travel of the web, and which can be moved to alterthe length of the travel path of the web.

After the wetting unit the web W travels to a calender C whose two firstrolls are illustrated in the drawing by rolls 3 and 4, forming acalender nip N therebetween through which the web W is passed. The nipin question can be the only nip of the calender C, or as shown in FIG.1, it is the first nip in a multi-roll calender in which there areseveral successive calender nips N in the travel direction of the web W.In the nip N the heated roll is naturally on that side on which the webhas been subjected to wetting. If the wetting has been conducted on bothsides, both roll surfaces can be heated.

The method and the apparatus are used especially in connection with amachine calender functioning as a direct extension for the papermakingprocess, but it is also possible to use them when a paper web from anintermediate storage is calendered at a separate working stage, whereinthe unwound paper is subjected to wetting before it is passed to thefirst calender nip.

By means of a sufficiently long residence time after adding liquid it ispossible to improve the uniform absorption of water in the direction ofthe plane of the paper web as well. In the following, some ways ofimproving the adding of liquid with the wetting devices 2 especially inthe direction of the plane of the web W will be described.

As was stated above, it has proved to be considerably difficult to applya sufficiently even water film for the purpose of calendering on thesurface of the paper by means of a spray jet. In present configurations,the uneven quality of the film manifests itself in an uneven calenderingresult and surface damages, such as drop markings. With a sufficientlylong absorption time these problems can be reduced. In the following,another way of improving the applying result especially when usingspraying in droplets, will be described.

The basic requirement for producing an even water film includeswell-functioning spray nozzles with a known function. It is difficult tofind such nozzles because in present applications the accuracyrequirements are insignificant, the manufacturing tolerances of thenozzles are too high in most cases, and it is very difficult to estimateand measure the function of the nozzles (droplet size distributions,coverage in the paper, the moisture transferred to the paper as well asthe uniformity of the moisture).

By using the present basic nozzles as wetting devices 2, it is possibleto attain an even water film in the wetting. The method is based on theknowledge of the water sorption capacity of the paper. Certain papergrade is capable of bonding and absorbing a particular water amount on afixed surface area in a given time unit. FIG. 6 shows schematically theprinciple in the spray wetting effected from underneath the web W.

If the water amount is statistically sufficiently larger than theaforementioned water sorption capacity, it is possible to adjust thewater amount by regulating the length of the jet in the machinedirection of the web, and thus an even water film is attained despitethe small irregularities of the jet. The water amount denotes the amountof liquid per surface area unit applied from the wetting device duringone time unit. The amount must be considerably larger so that the lossof water bouncing from the surface would be taken into account.

FIG. 6 shows a spray beam 2 a issued from a spray nozzle functioning asa wetting device. In the drawing, the designations in the longitudinaldirection of the web can also be treated as surface areas, since thephenomena prevail on the entire width of a standard width web W.

The contact time tc is d/Vw, in which d is the length of the spray beam2 a on the surface of the web and Vw is the speed of the web W. Thewater amount Vapp, the unit e.g. g/(m²×s), sprayed on the surface areaA1 covered by the jet, is dependent on the length d of the beam, and onthe spraying velocity of the nozzle. On the other hand, the web W has apaper-grade-specific water sorption capacity Vsorp, which indicates thecapability of the surface to absorb the water amount per surface areaand time unit, the unit also g/(m²×s). A water amount larger than thewater sorption capacity is sprayed, i.e. Vapp>Vsorp. In practice thisalso means that the absorption or imbibition time ti is longer than thecontact time tc, i.e. after the beam 2 a, there is an even liquid filmon the surface of the web W. When this is combined with a long influencetime before the calender, a very uniform wetting is attained.

By arranging the distance of the nozzle from the web W adjustable, it ispossible to alter the length d (surface area) of the beam 2 a e.g. intoa surface area A2, wherein Vapp is also changed while the flow rate(g/s) of the nozzles remains constant.

Vsorp is dependent on several factors, such as the composition of thepaper and the application conditions (air flows, linear velocity of thejet, spraying angle). This can be determined for paper grades inaccordance with the conditions.

It is advantageous to add an amount of liquid which effects the swellingof fibres into the web W at least in two successive points, wherein itis possible to apply smaller quantities at a time. Thanks to this, thewater can be directed to the surface layer that is important in view ofthe calendering result, which is significant e.g. when producing SCpaper grades. Even though a good effect is obtained with one addition,addition in portions in two or more successive points is advantageousespecially with increasing smoothness and/or hydrophobicity of the paperor if the form of the moisture gradient is important.

The absorption of water in successive portions into the web can bearranged in such a way that in the first adding point most of the addedwater has been absorbed in the web, while part of it remains as asurface water in the roughness volume of the paper or paperboard whenthe next portion is added. Thereafter it is possible to add a thirdportion at a stage where most of the surface water+the water added atthe preceding stage has again been absorbed in the web.

The act of applying a water film or other liquid applied by sprayingevenly on the surface of a moving web may thus require the use ofseveral sucessive water jets. When the web is moving at a high speed,the water jets must have a considerably high speed so that they can bebrought in contact with the web. Spraying experiments have revealedturbulence phenomena on the surface of the web, which are due touncontrolled flows of air. In FIG. 7a these turbulence zones are markedwith the letter Z.

In the turbulence zone the mixture of air and water bouncing from thesurface of the web migrates against the surface of the web and causesso-called “wind” marks on the surface of the web; i.e. quantitativefluctuation occurring at intervals of 5 to 10 cm, which impairs e.g. thecalendering result.

In FIG. 7b, control elements 5 are arranged between the jets 2 a or onboth or on one side of a single jet, depending on the spraying angle. Bymeans of the elements the mixture of air and water bouncing from thesurface of the web is directed in such a way that it does not interferewith the preceding water jet and end up on the surface of the web again,wherein the extremely harmful wind marks are eliminated. Thus, theelements also improve the controllability of the entire system. Thecontrol elements 5 can be for example walls directed towards the surfaceof the web W, which walls come sufficiently close to the surface of theweb so that the mixture of air and water which is located close to thesurface of the web collides with them. FIG. 7b illustrates spray-wettingunderneath the web, in which water can run downwards along the surfacesof the elements 5. The method can also be applied from other directions,e.g. for wetting effected from above, in which the elements can havesuch a structure that they do not spill water back to the web, i.e. theycan be for example water absorbent.

The invention is not restricted solely to the above-presenteddescription and drawings, but it can vary according to the appendeddrawings. Even though the preceding description is focused on thespray-wetting, the advantageous effects of the invention in thefinishing of paper or paperboard web can also be attained with otherwetting methods.

In particular, the invention can be applied for on-line papermaking inwhich the paper is dried after the formation down to a final moisturearea of 2 to 6%, and the target moisture in re-wetting is 8 to 11%.

The liquid to be applied is typically water, wherein it can be water assuch or contain other substances as solutes.

The treatment of the surface of the web conducted after the wetting is,in turn, of such a type that the wetting of the surface is useful. It isfor example mechanical moulding, possibly with a thermal treatmentconnected thereto. Calendering provides a practical example of such atreatment.

The present invention has been described herein with reference topreferred embodiments of the invention however the description providedherein is for illustrative purposes and should not be considered to beexhaustive. It is understood that modifications and variations of theabove describe preferred embodiments are possible without departing fromthe spirit or scope of the present invention.

What is claimed is:
 1. A method for the moistening of a paper web in apaper or paperboard making process, comprising the steps of: applying aliquid to a surface of said paper web while said paper web is passing apredetermined point in said process; passing said paper web to a surfacetreatment process in a calender having at least four nips; providing asufficient amount of absorption run time of said paper web between saidapplying of said liquid to said paper web and said passing of said paperweb to said surface treatment process such that at least 80% of anamount of said liquid which is absorbable by said paper web is absorbed;providing a paper web guiding system comprising a plurality of paper webguiding members structured and arranged between said point of applyingsaid liquid to said paper web and said passing of said paper web to saidsurface treatment process; and adjusting said absorption run time ofsaid paper web by changing a location of at least one of said paper webguiding members.
 2. The method according to claim 1, wherein said liquidis applied to said paper web at least 0.2 seconds before said passing ofsaid paper web to said surface treatment process.
 3. The methodaccording to claim 1, wherein said liquid is applied to said paper webbetween about 0.2 seconds and 2 seconds before said passing of saidpaper web to said surface treatment process.
 4. The method according toclaim 1, wherein said liquid is applied to said paper web between about0.5 seconds and 1.5 seconds before said passing of said paper web tosaid surface treatment process.
 5. The method according to claim 1,wherein said liquid is applied to said paper web in a spray wettingprocess.
 6. The method according to claim 1, further comprising the stepof guiding said paper web along a winding path between said point ofapplying said liquid to said paper web and said passing of said paperweb to said surface treatment process, wherein said winding path isformed by at least one guiding member.
 7. The method according to claim1, wherein said adjusting of said absorption run time of said paper webis effectuated by adjusting the location of at least one of said paperweb guiding members in a direction transverse a running direction ofsaid paper web.
 8. The method according to claim 1, wherein said paperweb guiding system comprises a pair of rows of guiding members each rowhaving at least two guiding members associated therewith over which saidpaper web travels, wherein said absorption run time is adjusted bychanging a location of at least one of said pair of rows of guidingmembers.
 9. The method according to claim 8, comprising the step of:adjusting absorption run time by changing a location of at least one ofsaid pair of rows of guiding members in a direction transverse a runningdirection of said paper web.
 10. The method according to claim 1,comprising the step of: applying an amount of liquid greater than asorption capacity of said paper web.
 11. The method according to claim10, comprising the steps of: applying said liquid to said paper web inthe form of a spray jet; and adjusting an amount of liquid applied tosaid paper web by adjusting a length of said spray jet in a runningdirection of said paper web.
 12. The method according to claim 11,comprising the step of: adjusting said length of said spray jet byadjusting a distance of spray nozzle, from which said jet is sprayed,from said paper web.
 13. The method according to claim 10, comprisingthe steps of: applying said liquid to said paper web in the form of aspray jet; and applying said spray jet to said paper web from underneathsaid paper web.
 14. The method according to claim 1, comprising the stepof: applying said liquid to said paper web in at least two portions on asame side of said paper web.
 15. The method according to claim 14,comprising the step of: applying said liquid to said paper web in atleast two successive spray wettings on at least one side of said paperweb.
 16. The method according to claim 1, comprising the step of:applying said liquid to said paper web by spray wetting through a jet;and controlling an air flow, created by said spray wetting, with atleast one control element structured and arranged on at least one sideof said jet in a travel direction of said web.
 17. The method accordingto claim 16, wherein said air flows created between a pair of successivejets is controlled by said at least one control element.
 18. The methodaccording to claim 1, wherein said applying of said liquid is applied inthe manufacture of SC paper and wherein said liquid is applied to apaper web coming from a drying section before an on-line calenderingstep.
 19. The method according to claim 18, wherein the paper web isdried to a final moisture area of 2% to 6% and is rewetted to a targetmoisture of 8% to 11% before said calendering step.
 20. The methodaccording to claim 1, wherein said applying of said liquid iseffectuated after a drying section in a paper machine.
 21. The methodaccording to claim 1, wherein said paper web guiding system comprises atof guiding members having at least two guiding members associatedtherewith over paper web travels, and between which the web is guidedover a guiding member excluded row of guiding members, wherein anabsorption run time is adjusted by changing a location of guidingmembers.
 22. An apparatus for the moistening of a paper web in a paperor paperboard machine, comprising: a calender having at least four nipsstructured and arranged for treating said paper web; at least one webwetting device, for adding a liquid to said paper web, structured andarranged before said calender in a machine running direction; whereinsaid at least one web wetting device is located a predetermined webrunning distance before said calender such that said liquid added tosaid paper web has sufficient time for at least 80% of the total amountof said liquid which said paper web can absorb is absorbed beforereaching said; and at least three rolls structured and arranged betweensaid calender and said at least one wetting device, said at least threerolls comprising a first roll and a last roll and being structured andarranged to guide said paper web along a winding path having an overalllength between the first roll and the last roll, and at least one ofsaid at least three rolls being structured and arranged to be changeableto another location such that the overall length of the path between thefirst roll and the last roll is changed to effect in a web runningdistance.
 23. The apparatus according to claim 22, wherein said at leastone web wetting device is located at the most 35 web running metersbefore said surface treatment member.
 24. The apparatus according toclaim 22, wherein said at least one web wetting device is locatedbetween about 5 and 25 web running meters before said surface treatmentmember.
 25. The apparatus according to claim 22, wherein said at leastone web wetting device is located between about 2 and 10 web runningmeters before said surface treatment member.
 26. The apparatus accordingto claim 22, further comprising: a roll system structured and arrangedbetween said surface treatment device and said at least one web wettingdevice, wherein said roll system comprises at least two rolls arrangedin at least one roll row; and wherein a location of at least one roll ofsaid roll system is structured and arranged to be changeable in at leastone of a transverse and longitudinal direction of said roll system,whereby a change in said location of said at least one roll effects achange in an overall travel length of said paper web within said rollsystem.
 27. The apparatus according to claim 26, wherein the roll systemcomprises a pair of roll rows each roll row having at least two rolls;and wherein a location of at least one of said pair of roll rows isstructured and arranged to be changeable in at least one of a transverseand longitudinal direction of said roll system.
 28. The apparatusaccording to claim 26, wherein a location of said at least one roll rowis changeable in a transverse web running direction.
 29. The apparatusaccording to claim 22, wherein said at least one web wetting device isstructured and arranged after a drying section of said paper orpaperboard machine.